Measuring device and measuring method

Abstract

To provide a measuring device capable of measuring displacement of a support member that movably supports a structure.SOLUTION: A measuring device 120 includes a control unit that acquires multiple images of a support member 80 that movably supports a structure 70, which are taken at different times during a load on the structure 70 is changing, measures the displacement of the support member 80 based on the multiple images and extracts principal components for the measured displacement of the support member 80.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to measuring the displacement of a support member that movably supports a structure. [Background technology]

[0002] As a technique for investigating the appearance of an object, for example, Patent Document 1 describes a technique for measuring crack width from an original image of a structure or product obtained through a camera. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-139285 A [Non-patent literature]

[0004] [Non-Patent Document 1] Tohru SHINKE, et al, ``PRACTICAL FORMULAS FOR ESTIMATION OF CABLE TENSION BY VIBRATION METHOD'', Proc. Jpn. Soc. Civ. Eng., No. 294, 1980 Summary of the Invention [Problem to be solved by the invention]

[0005] Even if there is no problem with the appearance of a support member that movably supports a structure, if the support member does not move as specified, unexpected stress may be applied to the structure or support member, which may result in damage to the structure or support member.

[0006] In view of this, the present disclosure provides a measurement device and a measurement method capable of measuring the displacement of a support member that movably supports a structure. [Means for solving the problem]

[0007] A measurement device according to one aspect of the present disclosure includes a control unit that acquires multiple images of a support member that movably supports a structure, the images being taken at different times while a load applied to the structure is changing, measures a displacement of the support member based on the multiple images, and extracts a principal component for the measured displacement of the support member.

[0008] Moreover, a measurement method according to one aspect of the present disclosure is a measurement method for measuring the displacement of a support member that movably supports a structure, which includes obtaining multiple images of the structure taken at different times when a load applied to the structure is changing, measuring the displacement of the support member based on the multiple images, and extracting principal components for the measured displacement of the support member. Effect of the Invention

[0009] According to an aspect of the present disclosure, a measurement device and a measurement method can measure the displacement of a support member that movably supports a structure. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an external view showing a configuration example of a measurement system according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing a side surface of a support member according to the embodiment. [Diagram 3] FIG. 3 is a block diagram illustrating a functional configuration of the measurement device according to the embodiment. [Figure 4A] FIG. 4A is a schematic diagram showing an example of a principal component of displacement in each local region. [Figure 4B] FIG. 4B is a schematic diagram showing an example of a principal component of the displacement in each local region. [Figure 4C] FIG. 4C is a schematic diagram showing an example of a principal component of the displacement in each local region. [Figure 4D] FIG. 4D is a schematic diagram showing an example of a principal component of the displacement in each local region. [Diagram 5]FIG. 5 is a flowchart of the measurement process according to the embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a plurality of images according to the embodiment. [Figure 7] FIG. 7 is an external view showing a configuration example of a measurement system according to another embodiment. [Figure 8] FIG. 8 is a schematic diagram showing an example of a principal component of the displacement in each local region. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (Summary of the Disclosure) A measuring device according to one aspect of the present disclosure includes an acquisition unit that acquires multiple images of a support member that movably supports a structure, the multiple images being taken at different times while a load applied to the structure is changing, and a measuring unit that measures the displacement of the support member based on the multiple images.

[0012] According to the measurement device having the above configuration, it is possible to measure the displacement of the support member that movably supports a structure.

[0013] The device may further include a determination unit that determines whether or not the support member is performing a prescribed movement based on the displacement of the support member measured by the measurement unit.

[0014] This allows a user of the measuring device having the above configuration to know whether or not the support member is moving in a specified manner.

[0015] Furthermore, the present invention may further include an extraction unit that performs multivariate analysis on the displacement of the support member measured by the measurement unit to extract principal components, and the judgment unit may make the judgment based on the principal components extracted by the extraction unit.

[0016] This allows the measurement device having the above configuration to determine whether or not the support member is performing a specified movement based on the characteristic component of the displacement components of the support member, making it possible to more accurately determine whether or not the support member is performing a specified movement.

[0017] The structure may be a bridge girder, the support member may be a bearing, and the specified movement may include rotation.

[0018] As a result, the measuring device having the above configuration can determine whether or not the bearing that rotatably supports the bridge girder is rotating as specified.

[0019] The structure may be a bridge girder, the support member may be a bearing, and the specified movement may include translation.

[0020] As a result, the measuring device having the above configuration can determine whether or not a bearing that supports a bridge girder in a translatable manner is performing a translational movement as specified.

[0021] The structure may also be a bridge girder of a suspended structure, the support member may be a cable of the suspended structure, and the specified movement may include movement vertical to the direction in which the cable is pulled.

[0022] As a result, with the measuring device of the above configuration, it is possible to determine whether the cable that movably supports the bridge girder of a suspended structure is displacing vertically in the direction in which it is pulled as specified.

[0023] In addition, the structure may be a bridge girder of a suspended structure, the support member may be a cable of the suspended structure, the extraction unit may determine the frequency of the cable or the tension of the cable from the frequency, and the judgment unit may make the judgment based on the frequency of the principal component extracted by the extraction unit or the tension.

[0024] This makes it possible to determine whether the vibration frequency at which a cable that movably supports the bridge girder of a suspended structure vibrates is as specified, or whether the tension at which the cable displaces is as specified.

[0025] The imaging device may further include an imaging unit that captures the plurality of images.

[0026] As a result, the measuring device having the above configuration can measure the displacement of the support member that movably supports the structure, without acquiring an image from outside.

[0027] A measurement method according to one aspect of the present disclosure is a measurement method for measuring the displacement of a support member that movably supports a structure, comprising: acquiring multiple images of the structure taken at different times while a load applied to the structure is changing; and measuring the displacement of the support member based on the multiple images.

[0028] According to the above-described measuring method, it is possible to measure the displacement of a support member that movably supports a structure.

[0029] Hereinafter, a specific example of a measuring device according to one aspect of the present disclosure will be described with reference to the drawings. Each of the embodiments shown here shows one specific example of the present disclosure. Therefore, the numerical values, shapes, components, arrangement and connection form of the components, steps (processes) and order of steps shown in the following embodiments are examples and do not limit the present disclosure. Among the components in the following embodiments, those not described in the independent claims are components that can be added arbitrarily. Also, each figure is a schematic diagram and is not necessarily illustrated strictly.

[0030] In addition, a comprehensive or specific aspect of the present disclosure may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0031] (Embodiment) [Inspection system configuration] First, a configuration example of a measurement system according to an embodiment will be specifically described with reference to Fig. 1. Fig. 1 is an external view showing a configuration example of a measurement system according to an embodiment. The measurement system 100 includes an imaging device 110 and a measuring device 120.

[0032] The imaging device 110 is, for example, a digital video camera or a digital still camera equipped with an image sensor. The imaging device 110 captures images over time of a support member 80 that movably supports a structure 70. In this embodiment, as an example, the structure 70 is a bridge girder, and the support member 80 is a bearing that is installed on a pier 90 and supports the bridge girder so that it can be driven and moved.

[0033] FIG. 2 is a schematic diagram showing a side view of a support member 80 in an example in which the support member 80 is a support.

[0034] As illustrated in FIG. 2, support member 80 includes a rotationally movable part 81 that can rotate around a rotation axis perpendicular to the plane of the drawing, and a translationally movable part 82 that can translate (slide) in the left-right direction (horizontal direction) of the drawing.

[0035] The support member 80 is configured to include a rotational movable part 81 and a translational movable part 82, thereby supporting the structure 70 (bridge girder) in a rotatable and translational manner. In this manner, the specified movement performed by the support member 80 includes rotation and translation.

[0036] The structure 70 does not necessarily have to be limited to a bridge girder, and the support member 80 does not necessarily have to be limited to a bearing. As an example, the structure 70 may be a compressor, and the support member 80 may be a damper that attaches the compressor to a wall surface of a building. As another example, the structure 70 may be a house, and the support member 80 may be a seismic isolation mechanism disposed between the foundation and the house. The seismic isolation mechanism may be, for example, laminated rubber.

[0037] Returning to FIG. 1, the description of the measurement system 100 will continue.

[0038] Specifically, the imaging device 110 captures an image of the support member 80 when the load on the structure 70 is changing. For example, if the structure 70 is a bridge girder and the support member 80 is a support, a plurality of images are captured when a vehicle is traveling on the bridge girder, when some force is applied to the bridge girder due to wind or the like, and the like.

[0039] The multiple images are images of the same portion of the support member 80, and are images captured at different times. Specifically, the multiple images are, for example, multiple frames included in a video.

[0040] The measuring device 120 is, for example, a computer, and includes a processor (not shown) and a memory (not shown) in which a software program or instructions are stored. The processor executes the software program, causing the measuring device 120 to realize a number of functions, which will be described later. The measuring device 120 may also be configured with a dedicated electronic circuit (not shown). In this case, the multiple functions, which will be described later, may be realized by separate electronic circuits, or may be realized by a single integrated electronic circuit.

[0041] The measuring device 120 is, for example, communicatively connected to the imaging device 110 and measures the displacement of the support member 80 based on a plurality of images captured by the imaging device 110.

[0042] [Functional configuration of the measurement device] Next, the functional configuration of the measuring device 120 according to the embodiment will be described with reference to FIG.

[0043] 3 is a block diagram showing a functional configuration of a measuring device 120 according to an embodiment. As shown in FIG. 3, the measuring device 120 includes an acquiring unit 121, a measuring unit 122, an extracting unit 123, a region identifying unit 124, a determining unit 125, and a prescribed movement identifying unit 126.

[0044] The acquisition unit 121 acquires a plurality of images of the support member 80 that movably supports the structure 70, captured at different times while the load applied to the structure 70 is changing. For example, the acquisition unit 121 acquires a plurality of images from the imaging device 110 by wireless communication. Alternatively, for example, the acquisition unit 121 may acquire a plurality of images from the imaging device 110 via a removable memory (e.g., a Universal Serial Bus (USB) memory).

[0045] The measuring unit 122 measures the displacement of the support member 80 based on the multiple images acquired by the acquiring unit 121. Specifically, the measuring unit 122 measures the displacement of each local area on the surface of the support member 80. The local area may be an area corresponding to one pixel, or an area corresponding to multiple pixels. The measuring unit 122 may calculate, for example, a motion vector of each local area as the displacement of each local area. In this case, the measuring unit 122 calculates the motion vector of each local area by estimating the motion of each local area using, for example, a block matching method.

[0046] The extraction unit 123 extracts principal components by performing multivariate analysis on the displacement of the support member 80 measured by the measurement unit 122. Specifically, the extraction unit 123 extracts principal components by performing multivariate analysis on the displacement of each local region included in a specific region identified by a region identification unit 124 described below, among the displacements of each local region measured by the measurement unit 122. As an example of the multivariate analysis, for example, principal component analysis is considered.

[0047] Figures 4A to 4D are schematic diagrams showing an example of principal components of displacement in each local region extracted by extraction unit 123 when the specific region specified by region specifying unit 124 is rotatable part 81. Figure 4A shows the first principal component of the displacement in each local region, Figure 4B shows the second principal component of the displacement in each local region, Figure 4C shows the third principal component of the displacement in each local region, and Figure 4D shows the fourth principal component of the displacement in each local region. Each arrow in Figures 4A to 4D indicates the direction of displacement and the distance of displacement in each local region.

[0048] As shown in FIG. 4D, the fourth principal component of the displacement in each local region of the rotatable part 81 indicates the rotation of the rotatable part 81.

[0049] Note that, as long as the extraction unit 123 is configured to extract principal components by performing multivariate analysis on the displacements of the support member 80 measured by the measurement unit 122, the extraction unit 123 is not necessarily limited to the example of a configuration in which the principal components are extracted by performing multivariate analysis on the displacements of each local region included in a specific region identified by the region identification unit 124, among the displacements of each local region measured by the measurement unit 122. For example, the extraction unit 123 may extract principal components by performing multivariate analysis on all the displacements of each local region on the surface of the support member 80.

[0050] The region identifying unit 124 identifies a specific region including a local region that is to be the target of extraction of a principal component by the extracting unit 123. The region identifying unit 124 may include, for example, a user interface (for example, a touch panel) and identify, as the specific region, a region designated by a user based on an input operation by the user using the measuring device 120. Furthermore, the region identifying unit 124 may identify, as the specific region, a region including a movable portion of the support member 80 by performing, for example, AI processing including image recognition processing on a plurality of images acquired by the acquiring unit 121.

[0051] The determination unit 125 determines whether the support member 80 is performing a prescribed movement based on the displacement of the support member 80 measured by the measurement unit 122. Specifically, the determination unit 125 determines whether the support member 80 is performing a prescribed movement based on the principal components extracted by the extraction unit 123. For example, when a principal component indicating a prescribed movement specified by a prescribed movement specification unit 126 described later is present among the principal components extracted by the extraction unit 123, the determination unit 125 may determine that the support member 80 is performing a prescribed movement, and when a principal component indicating the prescribed movement is not present, the determination unit 125 may determine that the support member 80 is not performing a prescribed movement. As an example, when the prescribed movement specified by the prescribed movement specification unit 126 is the rotation of the rotatable part 81, the determination unit 125 determines that the support member 80 is performing a prescribed movement when a principal component indicating the rotation of the rotatable part 81 is included among the principal components of the displacement in each displacement region extracted by the extraction unit 123, as illustrated in FIG. 4D.

[0052] In addition, the judgment unit 125 does not necessarily have to be limited to the example of a configuration based on the principal components extracted by the extraction unit 123, so long as it is configured to judge whether or not the support member 80 is moving as specified based on the displacement of the support member 80 measured by the measurement unit 122.

[0053] The prescribed movement identifying unit 126 identifies a prescribed movement performed by the support member 80. The prescribed movement identifying unit 126 may include, for example, a user interface (for example, a touch panel) and identify a movement designated by a user based on an input operation by the user using the measuring device 120 as the prescribed movement performed by the support member 80. Furthermore, the region identifying unit 124 may identify the prescribed movement performed by the support member 80 by, for example, performing AI processing including image recognition processing on a plurality of images acquired by the acquiring unit 121.

[0054] [Operation of measuring device] The operation of the measuring device 120 having the above configuration will be described below.

[0055] The measuring device 120 performs a measurement process as a characteristic operation thereof. Here, the details of the measurement process performed by the measuring device 120 will be described with reference to FIGS.

[0056] Fig. 5 is a flowchart of the inspection process performed by the measuring device 120. Fig. 6 is a diagram showing an example of a plurality of images in the embodiment.

[0057] The measurement process is a process of measuring the support member 80 that movably supports the structure 70 based on a plurality of images captured by the imaging device 110.

[0058] The measurement process is started, for example, when a user of the measurement device 120 performs an operation to start the measurement process.

[0059] When the measurement process is started, the acquisition unit 121 acquires a plurality of images of the support member 80 that movably supports the structure 70, which are captured at different times while the load applied to the structure 70 is changing (step S101).

[0060] For example, as shown in FIG. 6, the acquisition unit 121 acquires images 11 to 14 that include the same portion of the support member 80 and that were taken at different times.

[0061] When the multiple images are acquired, the measurement unit 122 measures the displacement of the support member 80 based on the multiple acquired images (step S102). More specifically, the measurement unit 122 measures the displacement of each local region on the surface of the support member 80 based on the multiple acquired images.

[0062] When the displacement of the support member 80 is measured, the region identifying unit 124 identifies a specific region including a local region to be extracted from a principal component by the extracting unit 123 (step S103). The region identifying unit 124 may, for example, identify a region designated by a user as the specific region, or may, for example, identify a region including a movable part of the support member 80 as the specific region by performing AI processing including image recognition processing on a plurality of images acquired by the acquiring unit 121.

[0063] The process of step S103 does not necessarily have to be performed after the process of step S102. For example, the process of step S103 may be performed in parallel with the process of step S102, or may be performed before the process of step S102.

[0064] When the specific region is identified, the extraction unit 123 performs a multivariate analysis on the displacement of the support member 80 to extract principal components (step S104). More specifically, the extraction unit 123 performs a multivariate analysis on the displacement of each local region included in the specific region identified by the region identification unit 124, among the displacements of each local region measured by the measurement unit 122, to extract principal components.

[0065] When the principal components are extracted, the prescribed movement identifying unit 126 identifies a prescribed movement performed by the support member 80 (step S105). The prescribed movement identifying unit 126 may, for example, identify a movement designated by a user as the prescribed movement, or may identify the prescribed movement by performing AI processing including image recognition processing on a plurality of images acquired by the acquiring unit 121.

[0066] The process of step S105 does not necessarily have to be performed after the process of step S104. The process of step S105 may be performed in parallel with the process of step S104, or may be performed before the process of step S104, for example.

[0067] When the predefined movement is identified, the determination unit 125 determines whether or not the support member 80 is performing the predefined movement based on the displacement of the support member 80 measured by the measurement unit 122. More specifically, the determination unit 125 determines that the support member 80 is performing the predefined movement when a principal component indicating the predefined movement identified by the predefined movement identification unit 126 is present among the principal components extracted by the extraction unit 123, and determines that the support member 80 is not performing the predefined movement when a principal component indicating the predefined movement is not present.

[0068] Finally, the determination unit 125 outputs, as the measurement result, the displacement of the support member 80 and the determination result as to whether or not the support member 80 is moving as specified (step S106). For example, the determination unit 125 displays the measurement result on a display (not shown). Also, for example, the determination unit 125 may transmit the measurement result to another device (for example, a smartphone or a tablet computer).

[0069] [Consideration] As described above, the measuring device 120 measures the displacement of the support member that movably supports the structure. Then, the measuring device 120 determines whether the support member is moving as specified. Therefore, a user who uses the measuring device 120 can obtain knowledge regarding the possibility of damage to the structure or the support member due to unexpected stress being applied to the structure or the support member.

[0070] (Other embodiments) While the measurement device according to one or more aspects of the present disclosure has been described based on the embodiment, the present disclosure is not limited to the embodiment.

[0071] For example, a cable-stayed bridge in which the structure is a bridge girder and the supporting members are cables will be described. Fig. 7 is an external view showing a configuration example of a measurement system according to another embodiment. In Fig. 7, a cable-stayed bridge 700 has a bridge girder 711 as a structure and cables 701-710 stretched on a main tower 712 as supporting members. The extraction unit 123 detects the areas of the cables 701-710 from an image of the cable-stayed bridge 700 using image recognition, obtains the movement of the cables 701-710 in a direction perpendicular to the direction in which they are pulled by the bridge girder 711 and the main tower 712, and extracts the frequency of the principal component for each cable.

[0072] Fig. 8 is a schematic diagram showing an example of the principal components of the displacement in each local region. Fig. 8 shows the results of extracting the first principal component 802 and the second principal component 803 of the displacement of one cable. In Fig. 8, the dashed line 801 indicates the position of the cable in a stationary state. As the specified movement, the amplitude value of the vibration may be used, or the frequency of each principal component may be obtained and it may be determined whether the frequency is within a specified numerical range. As the change in load, the load of a vehicle passing over a bridge girder 711, or forced vibration of the cables 701 to 710 by a hammer or manual vibration may be used.

[0073] Furthermore, the extraction unit 123 may calculate the tension of the cable from the frequency of the principal component and determine whether the tension of each cable is within a specified value range. The method of calculating the tension from the frequency of the cable can be the method described in Non-Patent Document 1, or the like.

[0074] Furthermore, in addition to cable-stayed bridges, structures having cables, such as suspension bridges and other suspension structures and power transmission structures, may also be included in the scope of the present invention.

[0075] Furthermore, as long as the spirit of the present disclosure is not deviated from, various modifications that would occur to those skilled in the art to the present embodiment, and forms constructed by combining components of different embodiments, may also be included within the scope of one or more aspects of the present disclosure.

[0076] For example, in the above embodiment, the measurement device does not include an imaging device, but may include an imaging device. In this case, the imaging device functions as an imaging unit that is a part of the measurement device.

[0077] Furthermore, multiple functional components included in the measurement device (such as an acquisition unit, a measurement unit, an extraction unit, an area identification unit, a determination unit, and a default movement identification unit) may be realized by distributed computing or cloud computing.

[0078] In the above-described embodiments, the block matching is used for the motion estimation, but the present invention is not limited to this. For example, the motion estimation may be performed by matching other local image features (e.g., HOG (Histogram of Oriented Gradients), SIFT (Scaled Invariance Feature Transform)).

[0079] Furthermore, some or all of the components included in the measurement device in the above-described embodiment may be configured as one system LSI (Large Scale Integration). For example, the measurement device 120 may be configured as a system LSI having an acquisition unit 121, a measurement unit 122, an extraction unit 123, a region identification unit 124, a determination unit 125, and a prescribed movement identification unit 126.

[0080] A system LSI is an ultra-multifunctional LSI manufactured by integrating multiple components on a single chip, and specifically, is a computer system that includes a microprocessor, ROM (Read Only Memory), RAM (Random Access Memory), etc. Computer programs are stored in the ROM. The system LSI achieves its functions when the microprocessor operates according to the computer program.

[0081] Here, we refer to it as a system LSI, but it may also be called an IC, LSI, super LSI, or ultra LSI depending on the level of integration. Also, the method of integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor. It is also possible to use an FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connections and settings of the circuit cells inside the LSI.

[0082] Furthermore, if a new integrated circuit technology that can replace LSI appears due to the progress of semiconductor technology or a derivative technology, it is possible to integrate the functional blocks using that technology. The application of biotechnology is also a possibility.

[0083] Moreover, one aspect of the present disclosure may be not only such a measurement device, but also a measurement method in which characteristic components included in the measurement device are included as steps. Another aspect of the present disclosure may be a computer program that causes a computer to execute each characteristic step included in the measurement method. Another aspect of the present disclosure may be a computer-readable non-transitory recording medium on which such a computer program is recorded.

[0084] In each of the above embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. Here, the software for realizing the inspection device of each of the above embodiments is a program such as the following.

[0085] In other words, this program causes a computer to execute a measurement method for measuring the displacement of a support member that movably supports a structure, by acquiring multiple images of the structure taken at different times when the load on the structure is changing, and measuring the displacement of the support member based on the multiple images.

[0086] The present disclosure is widely applicable to measurement devices that measure the displacement of a support member that movably supports a structure. [Explanation of symbols]

[0087] 70 Structures 80 Support member 100 Measurement System 110 Imaging device 120 Measuring Equipment 121 Acquisition Department 122 Measurement section 123 Extraction part 124 Area identification part 125 Judgment section 126 Default Motion Identifier

Claims

1. The control unit is configured to acquire a plurality of images of a support member that movably supports a structure, the images being captured at different times when a load applied to the structure is changing, measure a displacement of the support member based on the plurality of images, and perform a multivariate analysis on the measured displacement of the support member to extract a principal component that indicates a rotation of a rotational motion of a rotation movable part of the support member. Measuring equipment.

2. The control unit displays the displacement of the support member due to the extracted principal component. The measurement device according to claim 1 .

3. The control unit displays the direction of displacement and the distance of displacement of the principal component. The measurement device according to claim 2 .

4. The control unit determines whether or not the rotational movement of the rotation movable part of the support member is a prescribed movement, based on the displacement of the support member due to the extracted principal component. The measurement device according to claim 1 .

5. The structure is a bridge girder, The support member is a bearing. The measurement device according to claim 1 .

6. The support includes the rotationally movable part and the translationally movable part, and supports the bridge girder rotatably and translationally; The movement of the support includes the rotational movement and the translational movement. The measurement device according to claim 5.

7. The control unit determines whether or not the rotational movement of the rotating movable part of the support is moving as specified based on the displacement of the support due to the extracted principal component. The measurement device according to claim 5.

8. Further, an imaging unit for capturing the plurality of images is provided. The measuring device according to any one of claims 1 to 7.

9. A measurement method for extracting a principal component indicating rotation of a rotational motion of a rotation movable part of a support member that movably supports a structure, comprising: acquiring a plurality of images of the structure captured at different times while a load applied to the structure is changing; measuring a displacement of the support member based on the plurality of images; A multivariate analysis is performed on the measured displacement of the support member to extract a principal component indicating the rotation of the rotational movement of the rotation movable part of the support member. Measurement method.

Images